Plymouth Rock has been an important symbolbut one with varying meaningssince its "invention" in 1774 as part of an attempt to promote the Revolution's cause by associating it with the Pilgrims. In the 1820s Plymouth Rock became a symbol for New Englanders of that region's importance to the nation's history. In the 1850s abolitionists used the rock as a symbol of New England's opposition to slavery. In the late nineteenth century it was promoted as a symbol of the English roots of the American elite and their opposition to immigration. The rock, moved to a display in downtown Plymouth in 1774, was reinstalled on the shore under a protective canopy in 1880. In 1920 the Plymouth Antiquarian Society discovered a missing four-hundred-pound piece of the rockbeing used as a doorstep. In 1983 the society offered a piece of its rock to the Smithsonian, and in 1984 officials traveled to Plymouth to accept the gift.